The Core for this P50 contains four functional interactive units: 1) P50 Tissue Acquisition & Characterization (P50-TAC); 2) Database & Biostatistics; 3) MRI Imaging; and 4) Administration. These units were developed to support the activities of the research group during the previous round of support, and are being extended in their current form. The P50-TAC Unit is responsible for prospectively Identifying brain and spinal cord donors, conducting postmortem MRI imaging per protocol, expeditiously processing brain and spinal cord tissue postmortem, and performing standardized histological assessment of lesions for the specific purposes of Projects 1, 2 and 3. The Database & Biostatistics Unit will collaborate with the investigators to optimize study design, ensure statistical power, analyze data requiring statistical expertise, and to design, implement, and manage study databases. The MRI Imaging Unit will coordinate MRI imaging procedures; assure that each protocol results in acceptable Image quality; verify quality of primary MRI data; and assist with analysis of the data for Projects 3 and 4. The Administrative Unit will manage the budget, organize investigator and advisory committee meetings and assist with preparation of reports.